The algae isn’t all their fault, the farmers said. They are doing their best to limit the algae-feeding phosphorus runoff from their fields. And they don’t deserve to be demonized.

There are just a few problems with this ploy.

First, as the mayor astutely pointed out, anyone who wants to see how well pollution-reducing strategies are working ought to be looking at the lake, which was particularly putrid this summer, carpeted in a thick layer of algae.

The year 2019 is on track to be one of the worst algae seasons on record.

This despite very earnest and well meaning efforts from farmers throughout the state who have embraced better practices — well-funded by state and federal programs — that limit the amount of fertilizer running off their fields into waterways.

But even the Ohio Environmental Protection Agency’s own data showed last year that these voluntary pollution-control efforts were not making a dent in the overall amount of phosphorus pouring down the Maumee River into the lake.

And second, noticeably absent from the farms to which Mr. Kapszukiewicz was invited to tour were any livestock operations. And it is those livestock farms — particularly the large-scale concentrated feeding operations — that many believe are contributing the bulk of the runoff pollution to the lake.

There is some dispute about the data, but some environmental activists believe western Lake Erie basin’s 146 concentrated animal feeding operations produce the manure equivalent of sewage generated by the cities of Los Angeles and Chicago. That manure has to go somewhere, and it usually ends up going down the Maumee.

If Ohio’s agricultural lobby were sincere in their plea for public officials to stop pointing fingers at the wrong culprits, they would get behind calls for a scientific inventory of pollution sources, particularly in the Maumee River basin.

Of course, such an inventory is more likely to quantify just how much runoff is coming from every farm, including the CAFOs.

More than that, a scientific pollution inventory, which state and federal environmental authorities should call for, would set Ohio on a path to creating a pollution diet.

Creating a total daily maximum load would allow regulators to set pollution limits and then enforce them.

That’s the only real strategy for cleaning up Lake Erie and saving it from the annual toxic algae that threatens Ohio’s tourism and sport fishing industries, Toledo’s drinking water source, and the region’s quality of life.

If the agriculture lobby were serious about reducing runoff, they wouldn’t be inviting Toledo’s mayor to visit farms, they’d be inviting regulators.